The difference between muscle strength and muscle tension

Because many people do not have a deep understanding of muscle strength and muscle tone, they just think that this disease is common and there is no need to care about it. You should know that muscle strength and muscle tone are different, so don’t mix them together. In addition, mild, moderate and severe muscle tone are different, so everyone needs to understand, how big is the difference between muscle strength and muscle tone?

Basic Overview

The generation and maintenance of muscle tone is a complex reflex activity, and its reflex arc is called the "r-loop", which includes the afferent part of the r-loop (the receptors of the muscle tone reflex are the muscle spindles and tendon spindles) and the efferent part of the r-loop (the a motor neurons in the anterior horn cells of the spinal cord and the motor nuclei of the brainstem control the extrafusal muscles, and the r motor neurons send out Ar fibers to reach and control the intrafusal muscles). Lesions in any part of the reflex arc can cause changes in muscle tone.

Grading

Passive Movement (PROM) Muscle Tone Grading Criteria

Ⅰ Mild

Resistance occurs during the last quarter of the PROM, when the muscle is in its longest position.

Ⅱ Moderate

Resistance appears at 1/2 of the PROM.

III Severe

Resistance occurs during the first quarter of the PROM, when the muscle is in its shortest position.

Muscle strength refers to the force of muscle contraction when the limbs make voluntary movements. The examination method is to ask the patient to perform extension and flexion exercises on the joints of the upper and lower limbs in turn, and observe whether the muscle strength is normal, weakened or paralyzed by the resistance given by the examiner, and pay attention to the location of the paralysis. Generally, the upper limbs perform abduction and adduction of the upper arm, flexion and extension of the forearm, flexion and extension of the wrist, abduction and adduction of the fingers, and fist clenching. The lower limbs perform hip flexion, calf flexion and extension, plantar flexion and dorsiflexion, etc. If the condition requires, each muscle involved needs to be examined separately.

Inspection method

During the examination, the patient is asked to extend and retract his limbs, and the examiner applies resistance from the opposite direction to test the patient's ability to overcome the resistance, and pay attention to the comparison between the two sides. According to the muscle strength, muscle strength is generally divided into the following 0--5 levels, a total of six levels:

Grade 0: Complete paralysis, with no detectable muscle contractions.

Level 1: Only muscle contraction is detected, but no movement can be produced.

Level 2: The limbs can move parallel to the bed but cannot resist their own gravity, that is, they cannot be lifted off the bed.

Level 3: The limbs can overcome gravity and be lifted off the bed, but cannot resist resistance.

Level 4: The limbs can move against external resistance, but not completely.

Grade 5 muscle strength is normal.

Clinical significance

Different degrees of muscle weakness can be divided into complete paralysis and incomplete paralysis (paresis).

Paralysis of different parts or combinations can be named as follows: ① Monoplegia: paralysis of a single limb, more common in poliomyelitis; ② Hemiplegia: paralysis of one limb (upper or lower limb paralysis) often accompanied by unilateral cranial nerve damage, more common in intracranial damage or stroke; ③ Crossed hemiplegia: paralysis of one limb and contralateral cranial nerve damage, more common in brainstem lesions; ④ Paraplegia: paralysis of both lower limbs, the result of transverse spinal cord injury, more common in spinal cord trauma and inflammation.